## Abstract

Measurements of the beta-neutrino correlation coefficient (aβν) in nuclear

beta decay, together with the Fierz interference term (bF ), provide a robust test for the existence of exotic interactions beyond the Standard Model

of Particle Physics. The extraction of these quantities from the recoil ion

spectra in β-decay requires accurate knowledge, decay branching ratios, and

high-precision calculations of higher order nuclear effects. Here, we report

on a new measurement of the 23Ne β-decay branching ratio, which allows

a reanalysis of existing high-precision measurements. Together with new

theoretical calculations of nuclear structure effects, augmented with robust

theoretical uncertainty, this measurement improves on the current knowledge

of aβν in 23Ne by an order of magnitude, and strongly constrains the Fierz

term in beta decays, making this one of the first extractions to constrain both

terms simultaneously. Together, these results place bounds on the existence

of exotic tensor interactions and pave the way for new, even higher precision,

experiments.

beta decay, together with the Fierz interference term (bF ), provide a robust test for the existence of exotic interactions beyond the Standard Model

of Particle Physics. The extraction of these quantities from the recoil ion

spectra in β-decay requires accurate knowledge, decay branching ratios, and

high-precision calculations of higher order nuclear effects. Here, we report

on a new measurement of the 23Ne β-decay branching ratio, which allows

a reanalysis of existing high-precision measurements. Together with new

theoretical calculations of nuclear structure effects, augmented with robust

theoretical uncertainty, this measurement improves on the current knowledge

of aβν in 23Ne by an order of magnitude, and strongly constrains the Fierz

term in beta decays, making this one of the first extractions to constrain both

terms simultaneously. Together, these results place bounds on the existence

of exotic tensor interactions and pave the way for new, even higher precision,

experiments.

Original language | American English |
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Publisher | arXiv |

Number of pages | 20 |

Volume | 2107.14355 |

State | Published - 2021 |